Re: kernel: stop_machine: report (un)dead code (and feedback request)

From: Chris Wilson
Date: Thu Nov 26 2015 - 09:52:51 EST


On Thu, Nov 26, 2015 at 03:45:59PM +0100, Valentin Rothberg wrote:
> Hi Chris,
>
> your commit 4c477de14237 ("kernel: remove stop_machine() Kconfig
> dependency") has shown up in today's linux-next tree (20151126).
> The commit changes the #ifdef condition in kernel/stop_machine.c
> from/to:
>
> -#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
> +#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
>
> Although this change fixes certain configs on X86, the condition now is
> a tautology since CONFIG_SMP is already required to compile the file:
>
> kernel/Makefile:65:obj-$(CONFIG_SMP) += stop_machine.o
>
> AFAIU, we can safely remove this #ifdef?

That seems logical. The argument in favour of it would be to keep the
ifdeffery around the function defintion the same as the function
declaration in stop_machine.h.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre
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